abscisic acid

Abscisic acid, formerly known as abscisin II or dormin,
is a growth-inhibiting plant hormone (a sesquiterpene).
Abscisic acid is present in a variety of plant organs, including leaves,
buds, fruits, seeds, and tubers. It promotes senescence and abscission (shedding) of leaves, and induces dormancy in buds and seeds. It is antagonistic to growth-promoting hormones (see antagonist).